Adrenergic excitation plays a dominant role in adjusting the circulation to demands imposed in most major illnesses. Since much of our insight into adrenergic responsiveness is based on changes following acute hemorrhage, it is the aim of this investigation to provide information on basic adrenergic mechanisms involved in adjusting flow and resistance of spleen and kidney to discrete physiological stimuli in normovolemic conditions. Adult mongrel dogs anesthetized with pentobarbital will have splenic and renal venous flow diverted through one major vein for each organ and total venous flow measured for each from indwelling square wave electromagnetic venous flow probes. An adreno-femoral shunt will permit simultaneous determination of adrenal blood flow. Adrenal, splenic, renal and arterial blood samples will be drawn simultaneously and analyzed for epinephrine and norepinephrine by a single isotope derivative radio-enzymatic technique. Simultaneously measured adrenal epinephrine and norepinephrine release, splenic and renal norepinephrine and epinephrine uptake and splenic and renal vascular resistance will be determined. Three separate stimuli: insulin hypoglycemia, left atrial stretch receptor activation and innervated carotid sinus stimulation will be independently evaluated in three separate groups of experiments. For each of these stimuli the effects of adrenal denervation, splenic and renal denervation will be determined. The influence of angiotensin-II on splenic norepinephrine and epinephrine uptake and splenic vascular resistance will be studied in groups of normals, acutely anephric, and acutely anephric animals infused with intravenous angiotensin-II at 1, 10, and 100 ng/kg/min.